What We Can DO To Reduce lighting pollution with street light design?
Introduction
Humans and their innovations are mostly to blame for the environmental degradation that occurs on Earth. Despite the fact that a variety of technology, like vehicles, plastics, and lighting, have made life more convenient for people. But now a variety of issues are emerging, such as the primary cause of climate change being automobile emissions and the overpopulation of plastic on our planet (soil and ocean). While though lighting improves living at night (street lights help us find our way home, industrial lighting keeps us safe, and residential lighting keeps our houses cozy and bright), it also has a detrimental effect on the environment. Human health, animal behavior, and the environment are all being impacted by light pollution, which is the excessive or improper use of outdoor artificial light.
A major contributor to the issue of light pollution is sky glow. Sky glow, which primarily occurs in metropolitan areas, is the brightening of the night sky as a result of illumination from vehicles, street lights, workplaces, industries, outdoor advertising, parking lots, and buildings. The photograph below was captured by a NASA satellite in 2016. (via a computer-generated world map of night sky brightness). The atlas depicts how and where our world is lighted at night and is accessible online at the linked NASA website (https://earthobservatory.nasa.gov/features/NightLights).
What exactly is light pollution?
When artificial light is introduced into the environment as a result of human and animal activity, either directly or indirectly, light pollution is created. Since it may endanger people's health, quality of life, and the preservation of the environment, excessive artificial light is classified as a pollution. Light pollution is a result of artificial light waste or overuse, which includes the following:
1. as a result of excessive lighting on the target
2. because light scatters or escapes directly to the sky or horizon.
3. because the illumination of the target occurs unnecessarily.
The natural darkness of the night has been altered by all of the aforementioned factors, which has a detrimental impact on health and organisms.
Lighting pollution's effects
- Impacts on people: Both humans and animals' natural circadian cycles can be severely disrupted by artificial light. Circadian rhythms can be thrown off by light at night. an internal 24-hour clock that regulates physiological processes and controls daily activity in almost all living things. The creation of the hormone melatonin, which is produced in the dark and inhibited in the presence of light, is one of these processes. Increasing light at night decreases melatonin synthesis, which can cause various health issues including sleep deprivation, exhaustion, headaches, stress, and anxiety. While there have been studies on the possible dangers of exposure to nocturnal light, recent research has also demonstrated a connection between cancer risk and decreased melatonin levels. Human melatonin levels have been observed to decrease in response to blue light. Light-emitting diodes (LEDs), which are popular for household, industrial, and urban lighting because of their energy efficiency and long life, as well as mobile phones and other computer devices all generate blue light.
- Impacts on Animals: Research has found that light may make animals dizzy and confused. Animal behavior, including migratory patterns, waking sleep patterns, and habitat development, is still impacted by light pollution. Light pollution can result in the loss and death of turtles and birds that would otherwise migrate under the guidance of the moon. Light pollution causes a significant number of insects to be drawn to artificial light and die, as well as having an impact on birds and other creatures that mostly eat these insects.
Guidelines for effective street lighting
Lighting should serve a purpose that is obvious, i.e.
We must determine if the illumination is actually essential before adding new fixtures or replacing old ones. We can make a decision on demand if there are alternatives. For instance, we may decrease the installation of some exterior lighting systems by applying reflective paint on signs and steps.
Lights should be directed and have clearly defined regions.
Without disturbing the vegetation and homes on either side of the road, road lighting should illuminate the roadbed. The stadium should be illuminated by stadium lights without disturbing the surrounding homes. We suggest that when designing lamps and lanterns, we should restrict the emission of light to the upper hemisphere and the beam should hit the ground as much as possible. To do this, we must make sure that lateral light distribution is designed based on the width of the road and the height of the street light installation.
Lights should be modest level and not brighter than necessary.
For different places, lighting laws have particular illuminance criteria. For instance, the lighting standards for indoor work places (EN 12464), stadiums (EN 12193), and streets (EN 13201), among others. We should employ the lowest lighting level available in order to satisfy the lighting requirements. Also, we must assess lighted surfaces since some of them could reflect too much light back into the night sky.
Lights should be regulated and have a set time.
To guarantee that lights are switched on when needed, muted when not enough light is needed, and shut off when not needed, outdoor lighting should have set illumination periods utilizing technologies like light controllers, timers, or motion detectors. The same is true for interior lighting; depending on the time of day and usage, we may reduce the illumination intensity or entirely switch off the lights by using dimmers, motion sensors, and smart controls.
Less blue light, or lighting with a warmer CCT, should be used.
The range of visible light's spectrum spans 390 to 780 nanometers. According to studies, blue light poses risks to both people and animals when it is emitted at wavelengths between 380 and 499 nm. The emission of the blue portion of the visible spectrum must be reduced, and quantities must be kept to a minimum. Blue light is thought to make up a smaller portion of a low color temperature's spectral spectrum. Regulations have also started to set limits on the amount of blue light content (light output below 500 nm), calling for it to be between 5% and 10% lower.
Suggestion for improving the architecture of street lights to lessen illumination pollution
We have included a list of lighting guidelines for excellent lighting practices that can reduce the impact on people and animals using outdoor lighting as an example. We believe that the following factors should be taken into account in order to reduce lighting pollution: the installation angle of the lamp, the design of the spectrum, the lighting design, the configuration of the power supply, and the use of lamp LEDs. We will go over each of these factors individually below：
a. Direct low-angle lighting
Steer clear of illuminating the night sky at an angle above the horizon. To start, pick a glass or sunshade option for the light to lessen its upward or backward emission. The ability to put lights in the center of the road due to public illumination can help the lamps have a good light distribution on the lateral distribution. If the lateral distribution is poor due to inadequate spectrum design, a tilting angle of 0 to 15 degrees is not permitted in order to prevent light from being cast into the sky.
b. Apply light to the lit surface as much as possible.
The light beam of the lamp should be focused on the useful region that needs to be lighted in an acceptable lighting distribution, rather than irradiating the nearby area that does not. Utilization is a metric that may determine how successfully light output is focused on the intended application. It can inform us of how much light is wasted and contributes to light pollution, as well as how much light is projected in valuable areas. We advise an usage of at least 75% for standard illumination.
c. Avoid using too much lights.
First off, there are established lighting standards for each type of illumination. You should be clear about the illumination level you require as the project implementer. When simulating lighting, we should utilize the fewest fixtures and watts necessary to illuminate the required area. Avoid using luminaires with excessively high luminous intensities and applying illumination to surfaces that aren't essential. The numerous road lighting standards are well explained in EN12301, which was stated in the preceding chapter. To determine the proper amount of illumination to illuminate the road, we should adhere to the related requirements, and the real illumination level should be kept within the range of 100–120% of the minimal norm.
d. The use of a lighting control system.
The availability of lighting control choices coincides with the widespread adoption of solid-state lighting in our daily lives. This enables them to dim the luminaires without affecting performance to accommodate varied working hours' illumination demands. With the use of sensors, pre-programmed dimming profiles, or wireless signals, the lighting management system may modify public illumination (for walkers and cars) in accordance with the density of usage of streets, squares, walkways, residential areas, and vehicle roadways. The following are some of the more prevalent ones found on street lamps:
- Dimming on a timer: This feature allows you to change the lamp's output at night. Just the dimming profile has to be programmed into the LED driver for this feature; the LED driver will then automatically execute dimming in accordance with the dimming profile. We can do this to make the sky darker after midnight.
- Constant lumen output: The CLO function is used to account for the luminous flux's progressive decrease throughout use as the lumen of the light source will eventually wane. We may alter the lamp's dimming profile using the TM21 curve (built-in driver). In order to make up for the lamp's diminished luminous flux while it is in operation, the power supply gradually adjusts the output current to raise the wattage of the lamp. As a result, while considering lumen degradation, we don't need to utilize bulbs with greater wattages.
- Motion sensor: A motion sensor is an occupancy sensor that turns on when it detects motion and remains on for a predetermined period of time. This indicates that because the motion sensor is activated, only persons who are beneath or close to the street lights will experience full illumination. To make the street light more ecologically friendly, it will lower the lighting or even turn the lamp off while nothing is within its range.
e. Reduce the amount of cold light used.
Cold light in outdoor lighting frequently provides viewers with a clear and concentrated visual experience. On the other hand, warm light makes individuals feel cozier and reduces visibility. Choosing between cold and warm light under public lighting is a common occurrence, but by taking into account the amount of blue light present in each color temperature, we think you'll be able to make an informed decision more quickly. Warm light has a color temperature between 2700 and 4000, whereas cold light typically has a color temperature between 5000 and 6500. In the latter, the percentage of blue light is considerably lower. Nowadays, amber lighting has a color temperature between 1800 and 2000 K and contains 10% or less blue light (based on LED chips model and correlated color temperature). The amount of blue light that lights emit is already governed by laws in several nations. For instance, Chile requires that the amount of light radiation below 500 nm be less than 10%, whereas the Czech Republic mandates a smaller amount.
Summary
There is an urgent need to address lighting pollution, but some regions (such as Africa) also require an urgent update to their infrastructure. At this point, street light selection, installation, and control assume a significant role. While rebuilding street lights in developed regions, we must avoid using excessive or unsuitable lighting, and if circumstances allow, we can outfit them with sophisticated control systems. The installation angle and spectrum choice of street lighting should be the primary considerations in less developed regions. Try to offer customers the option of a timer, a more conventional and useful dimming solution, so that the illumination can be dimmed in the second half of the night to reduce lighting pollution and keep people from returning to the old practice of over-illumination in developed areas. This can also help save energy (lower government spending). By reading this article, we hope that everyone will have a better knowledge of light pollution and its risks. We also hope that it will help street lighting designers, producers, purchasers, and users make decisions that will have the least negative effects on the environment. When it comes to economic growth without negatively impacting the environment too much.
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